The general opinion in cosmology regarding the shape of the universe is that it is still an open question and not definitively known. Cosmologists have proposed various possibilities for the shape of the universe, including flat, open, and closed geometries. Among these possibilities, a torus-shaped universe is one of the theoretical models that has been considered.
In a torus-shaped universe, the spatial geometry would resemble that of a donut or a bagel, with the universe wrapping around itself. This concept comes from the field of topology, which studies the properties of objects that remain unchanged under continuous transformations, such as stretching or bending. A toroidal universe would have a finite volume but no boundaries.
While the idea of a torus-shaped universe is intriguing, it is important to note that it remains speculative and lacks observational evidence to support or refute it. Current cosmological observations, such as the cosmic microwave background radiation and the large-scale distribution of galaxies, have provided strong evidence for a spatially flat universe on average. However, these observations are not conclusive and do not rule out more complex or exotic geometries.
In summary, while a torus-shaped universe is a concept that has been explored in cosmology, it is still considered a speculative idea without definitive evidence. The true shape of the universe is an active area of research, and cosmologists continue to study and develop models that best fit the available observational data.